Key strip for concrete pavers

ABSTRACT

A slip form paver includes the side forms for the concrete which is placed on the grade over which the paver moves. One side face of the concrete is formed with a longitudinally extending recess or keyway into which the concrete of the adjoining slab is to extend to form a mechanical interlock. The recess is formed by a metal strip which is bent to form the keyway. The keyway forming apparatus includes a punch which is operated by the movement of the strip and punches the strip so that projecting tabs extend into the concrete and serve to retain the strip in place and also provide the apertures in the strip for insertion of the tie bars.

I United States Patent 1 1 nu 3,876,323 Williams Apr. 8, 1975 [54l KEY STRIP FOR CONCRETE PAVERS 3.603.222 9/1971 Heltzel v. Jill/8 3.6 9 I 4U '01 1751 lnventori Richard A. Williams, Madison. lnd. 7 [73] Assignee: Rexnm-d Inc Milwaukgmwi Pl'illltlf) E\'umi'ner-Nile C. Byers Jr,

[22] Filed: Mar. IS. 1973 I57] ABSTRAUF llll App N0 3 A slip form pater includes the side forms for the concrete which is placed on the grade mm which the [52] us CL Hm-l paver moves. One side face of the concrete is formed [5H In Cl 21/02 with a longitudinally extending recess or kc way into [58] Field 7g which the concrete of the adjoining slah is to extend i to form a mechanical interlock, The recess is formed i n by a metal strip which is bent to form the keyway. The [96 References Cited keyway forming apparatus includes a punch which is UNITED STATES P TENTS operated by the movement of the strip and punches A V the strip so that projecting tabs extend into the con- 1.546.1U7 7/1925 Robb i. 404/100 Crete d Scrvc to retain the strip in place and also provide the apertures in the strip for insertion of the 5:463:1J6l 8/1969 3.491.661 l/I97t) 10 Claims. ll Drawing Figures PATENTEUAFR 8295 3876.323

SIiZEI 1 of 2 w" 1 H M i; in

KEY STRIP FOR CONCRETE PAVERS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to apparatus for forming the concrete of a roadway.

2. Prior Art The patents of M. I. Hudis. US. Pat. Nos. 3.491.661 and 3.5 30.776. show apparatus for forming metal strips to form the keyway and also means for inserting the tie bars through holes which are punched at intervals in the strip. The tie bars can also be inserted in the concrete by piercing the strip with the end of each tie bar as it is inserted. that is. without the prior punching of holes in the strip. However, with either method as well as where no tie bars have been inserted. long sections of the strip tend to become loose from the concrete slab after it has hardened. These loose sections would interfere with laying the next adjacent slab and must be removed in any case. Such removal generally involves removal of the entire strip with inconvenience and ex pense.

SUMMARY OF THE INVENTION The present invention is intended for use with slip form pavers and provides a keyway forming apparatus providing the holes for the tie bars by means ofa rotary punch which is operated by the forward motion of the paver. Additionally or especially. the strip is formed with projecting tabs which extend into the concrete slab and serve to retain the strip in place indefinitely thereafter BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a slip form paver and of the strip forming apparatus extending forwardly thereof.

FIG. 2 is a plan view of one side ofthe slip form paver and of the apparatus shown in FIG. 1.

FIG. 3 is an enlarged front elevation of the paver and shows a roll of the strip carried by the frame of the ap paratus.

FIG. 4 is a plan view of the apparatus shown in FIG. 3.

FIG. 5 is a plan view of the rotary punch over which the strip is drawn and of the roller assemblies through which the strip is drawn. The periphery of the upper and lower guide flanges is shown in broken lines.

FIG. 6 is a cross-section taken on line 66 of FIG. 5.

FIG. 7 is a side elevation ofthe roller assembly shown in FIG. 6.

FIGS. 8 and 9 are sections taken at 88 and 9-9 respectively of FIG. 7.

FIG. 10 is a cross-section of the edge of the concrete and showing the projecting tab.

FIG. 11 is an enlarged cross-section which shows the keyway strip and a tie bar in place in the side ofa slab of concrete at the rear of the machine as shown in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The slip form paver 21 shown in the drawings includes a frame 22 which extends over the grade G. The crawler 23 supports the right side of frame 22 which is shown and operates on grade G alongside the laid concrete. A similar crawler supports the left side of frame 22 and the two crawlers are driven to move the paver forwardly in operation. The paver also includes side forms which form the sides of the concrete and move forwardly with the paver. One side form 24 is shown. The plastic concrete C is deposited on grade G ahead of paver 21 and between the two side forms. The tools of the paver spread the concrete fully to the two side forms and smooth and finish the surface as the paver moves forwardly. A semi-plastic slab of concrete is left behind the paver which requires no supporting forms except the keyway strip which is left embedded in the right side of the concrete slab as will be described.

The keyway strip forming apparatus 31 includes the frame 32 which is carried by the paver 21 ahead of the side form 24. Vertical adjustment of frame 32 relative to the paver may be provided such as by the threaded rod 33. A rolled supply ofthe strip 35 is carried by the reel 36 from which the strip is drawn. A larger supply of the strip might instead be carried by the frame 22 of the paver. The strip 35 extends below the angular roller 37. forwardly between rolls 38 and past the guide 39 and around the rotary punch wheel 40. The strip fits between the upper and lower flanges 4| of the rotary punch wheel 40 and extends rearwardly through the vertical forming rolls 42-47 shown in FIGS. 5 and 7-9,

and alongside the inner face of side form 24. The strip as formed is troughed to include upper and lower flanges and a vertical center section so that forms the desired keyway in the side of the concrete as shown in FIGS. [0 and II.

At the start of paving with the initial use of the key strip 35, the end of the strip is first passed between rolls 38. around wheel 40 and drawn through forming rolls 42-47. The formed strip is then manually drawn from the protective shield 56 of frame 32 and rearwardly to extend alongside the side form 24 of paver 21. A wrench may be placed on the hexagonal cap 57 of wheel 40 for assistance in manually operating the apparatus and piercing the strip so that the end of the strip may be secured to the stake S or to the strip, not shown, which is already in place.

Wheel 40 is supported by bearings 6l on the vertical spindle 62 fixed to frame 32 and carries the two projecting replaceable punches 63 and 64. Strip 35 rotates wheel 40 and is alternately pierced by punches 63 and 64 which are shaped to form the strip with a series of projecting tabs 65 and 66 which will be further described.

The forming rolls 42 and 43 and the spring supported roll 44 effect the initial bending of strip 35. As shown in FIG. 8. the strip 35 is held between roll 44 and the adjacent cylindrical ends 42a and 43a of rolls 42 and 43 which are spaced to allow the tabs 65 and 66 to pass therebetween.

As shown in FIG. 9, forming rolls 45 and 46 and the spring-supported roll 47 similarly effect a second further bending of the strip.

Rolls 42-47 are carried by frame 32 and extend into the protective shield 56 of frame 32. The frame 32 is provided with an opening behind shield 56 and opposite the projecting platform 69 through which the bent tie bars may be inserted by any of various methods. As shown in FIG. II, one part of the tie bar 71 extends through strip 35 and into the concrete and the other part extends at a right angle thereto so that it does not project from the keyway formed by the strip and so that it does not interfere with the side form 24 of the paver as it moves past the bar. Other means. not shown. may be prmided instead for the insertion of the tie bars. where desired.

Punches 63 and 64 of wheel 40 are oppositely spaced and oppositely disposed. The smaller punch 64 is arranged so that the strip engages the punch and assures rotation of the wheel as the sharp leading edge of the larger punch 63 approaches and pierces the strip,

A spacing of 30 inches between tie bars 71 is typical and accordingly. wheel 40 is of that circumference. That is. only punch 63 may be needed to provide the apertures for the tie bars. However. punch 64 is set at lt-it) respecting punch 63 to assure the full rotation of wheel 40 and the spacing referred to. For that purpose. punch 64 is reversed as shown with respect to punch 63.

Both tabs 65 and 66 serve to secure the keyway in place not only until the concrete of the slab has hardened but until after the tie bars have been straightened and the strip is to be removed or until after the adjacent slab has been completed with the strip remaining in place between the two slabs.

The tabs may he formed with a power operated punch but the use of the forward movement of the paver to effect the punching is more simple and dependable in operation.

When the paver 21 has reached the end of the rolled supply of the strip carried by reel 36. a new supply may be placed on reel 36. The end of the strip which is in place and the leading end of the new supply may be readily spliced by crimping their edges or by welding. The splice readily passes between the forming rolls. Preferably. however. the end of the strip which is in place should be trimmed so that the splice passes around wheel 40 between the two punches 63 and 64.

l claim:

1. Apparatus for continuously forming a key strip from a supply of flat stock immediately ahead ofa concrete roadway pav er as it moves forwardly in operation. said apparatus comprising:

a. guide means through which the flat stock may pass;

b. a rotatable cutter wheel around which the stock is drawn solely by the forward motion of the apparatus. said cutter wheel being provided with a first projecting punch which punches the center section of the stock to provide it with tabs which project into the concrete for securement of the key strip; and

c. a pair of forming rolls rotated solely by the forward motion of the apparatus for forming the stock into a troughed-section key strip. said forming rolls being spaced to allow passage of the tabs therebe tween without coming into contact with any other structure. thereby permitting the tabs to pass between the forming rolls without damage to the tabs.

2. Apparatus as claimed in claim 1 wherein said cutter wheel has at least a second projecting punch on the periphery thereof and located so as to be effective to engage the stock and to rotate said cutter wheel while said first punch is piercing the stock.

3. The apparatus of claim 1 wherein said first punch is of a size larger than that ofa tie bar and provides the strip with apertures for the insertion of the tie bars through the strip and into the concrete.

4. The apparatus of claim I wherein the forming rolls comprise a flat roll which is disposed to engage the side of the [lat stock opposite the projecting tab and upper and lower forming rolls disposed to engage the side of the flat stock from which the tabs project. said latter rolls being vertically spaced to allow the tabs to pass therebetween and including cylindrical portions and tapered portions. the cylindrical portions and the cylindrical roll being oppositely disposed to hold the flat stock therebetween the tapered portions bend the upper and lower margins of the flat stock to form the keyway strip.

5. The apparatus of claim 4 which includes a series of such forming rolls. the larger ends of the tapered portions of each series being of progressively increasing size.

6. Apparatus for continuously forming a key strip from a supply of flat stock immediately ahead of a concrete roadway paver as it moves forwardly in operation. said apparatus comprising:

a. guide means through which the flat stock may pass; h. a pair of forming rolls rotated solely by the forward motion of the apparatus for forming the stock into a troughed section key strip. and

c. a rotatable cutter wheel around which the stock is drawn solely by the forward motion of the appara' tus. said cutter wheel being provided with a first projecting punch which the forward motion of the apparatus causes to punch the center section of the stock to provide it with tabs which project into the concrete for securement of the key strip.

7. Apparatus as claimed in claim 6 wherein said cutter wheel has at least a second projecting punch on the periphery thereof and located so as to be effective to engage the stock and to rotate said cutter wheel while said first punch is piercing the stock.

8. The apparatus of claim 6 wherein the forming rolls comprise a flat roll which is disposed to engage the side of the flat stock opposite the projecting tab and upper and lower forming rolls disposed to engage the side of the flat stock from which the tabs project. said latter rolls being vertically spaced to allow the tabs to pass therebetween and including cylindrical portions and tapered portions. the cylindrical portions and the cylindrical roll being oppositely disposed to hold the flat stock therebetween as the tapered portions bend the upper and lower margins of the flat stock to form the keyway strip.

9. The apparatus of claim 6 which includes a series of such forming rolls the larger ends of the tapered portions of each series being of progressively increasing size.

10. The apparatus of claim 6 wherein said first punch is of a size larger than that of a tie bar and provides the strip with apertures for the insertion of the tie bars through the strip and into the concrete. 

1. Apparatus for continuously forming a key strip from a supply of flat stock immediately ahead of a concrete roadway paver as it moves forwardly in operation, said apparatus comprising: a. guide means through which the flat stock may pass; b. a rotatable cutter wheel around which the stock is drawn solely by the forward motion of the apparatus, said cutter wheel being provided with a first projecting punch which punches the center section of the stock to provide it with tabs which project into the concrete for securement of the key strip; and c. a pair of forming rolls rotated solely by the forward motion of the apparatus for forming the stock into a troughed-section key strip, said forming rolls being spaced to allow passage of the tabs therebetween without coming into contact with any other structure, thereby permitting the tabs to pass between the forming rolls without damage to the tabs.
 2. Apparatus as claimed in claim 1 wherein said cutter wheel has at least a second projecting punch on the periphery thereof and located so as to be effective to engage the stock and to rotate said cutter wheel while said first punch is piercing the stock.
 3. The apparatus of claim 1 wherein said first punch is of a size larger than that of a tie bar and provides the strip with apertures for the insertion of the tie bars through the strip and into the concrete.
 4. The apparatus of claim 1 wherein the forming rolls comprise a flat roll which is disposed to engage the side of the flat stock opposite the projecting tab and upper and lower forming rolls disposed to engage the side of the flat stock from which the tabs project, said latter rolls being vertically spaced to allow the tabs to pass therebetween and including cylindrical portions and tapered portions, the cylindrical portions and the cylindrical roll being oppositely disposed to hold the flat stock therebetween as the tapered portions bend the upper and lower margins of the flat stock to form the keyway strip.
 5. The apparatus of claim 4 which includes a series of such forming rolls, the larger ends of the tapered portions of each series being of progressively increasing size.
 6. Apparatus for continuously forming a key strip from a supply of flat stock immediately ahead of a concrete roadway paver as it moves forwardly in operation, said apparatus comprising: a. guide means through which the flat stock may pass; b. a pair of forming rolls rotated solely by the forward motion of the apparatus for forming the stock into a troughed-section key strip; and c. a rotatable cutter wheel around which the stock is drawn solely by the forward motion of the apparatus, said cutter wheel being provided with a first projecting punch which the forward motion of the apparatus causes to punch the center section of the stock to provide it with tabs which project into the concrete for securement of the key strip.
 7. Apparatus as claimed in claim 6 wherein said cutter wheel has at least a second projecting punch on the periphery thereof and located so as to be effective to engage the stock and to rotate said cutter wheel while said first punch is piercing the stock.
 8. The apparatus of claim 6 wherein the forming rolls comprise a flat roll which is disposed to engage the side of the flat stock opposite the projecting tab and upper and lower forming rolls disposed to engage the side of the flat stock from which the tabs project, said latter rolls being vertically spaced to allow the tabs to pass therebetween and including cylindrical portions and tapered portions, the cylindrical portions and the cylindrical roll being oppositely disposed to hold the flat stock therebetween as the tapered portions bend the upper and lower margins of the flat stock to form the keyway strip.
 9. The apparatus of claim 6 which includes a series of such forming rolls, the larger ends of the tapered portions of each series being of progressively increasing size.
 10. The apparatus of claim 6 wherein said first punch is of a size larger than that of a tie bar and provides the strip with apertures for the insertion of the tie bars through the strip and into the concrete. 